As the critical dimension of metal oxide semiconductor field effect transistor (MOSFET) devices continues to shrink, the short channel effect becomes more problematic. Fin field effect transistor (FinFET) devices have good control capability of gates to effectively suppress the short channel effect. FinFET devices can also reduce random dopant fluctuation to improve the device stability. Thus, FinFET devices are widely used in the design of small-sized semiconductor elements.
In radio frequency (RF) circuit, the variable capacitance (varactor) MOS transistor is an important component. In the manufacturing process of a fin-type varactor MOS transistor, after the removal of an initial dummy gate polysilicon, the epitaxially formed source and drain have an irregular morphology, thereby affecting the device performance.